LEFT SIDE OF CAR LOWER

2006 Nissan Wingroad • 42,000 miles

Here's my problem, I own a Nissan AD wagon, but I started noticing that the front left side of the care is a bit lower, mostly when I have people in my car. We thought it was the shock and spring but we changed it twice and the problem still there. Just the other day we parked the car in a level spot, we started the engine and as soon as we changed the gear the left side droped. None of us seemed to know why is was so I real confused. I know very little about cars but my mechanic does not even know whats the cause and he told me that its normal. I had another mechanic check it out they said that not supposed to happen and was even more baffled as the car just remained a bit lower on the left. What do u presume is the problem?